Projection-type image display device and projection-type image display system

ABSTRACT

A projection-type image display device includes an image light generator configured to generate image light, a projection optics configured to project the image light onto a screen. The projection optics includes a reflection mirror configured to reflect the image light toward the screen, the image light outputted from the image light generator. A projection-type image display device includes a protective cover provided on an optical path of the image light reflected by the reflection mirror. The protective cover has a transmissive region transmitting the image light reflected by the reflection mirror.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2006-269965, filed on Sep. 29,2006; and Japanese Patent Application No. 2007-228102, filed on Sep. 3,2007; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection-type image display deviceand a projection-type image display system, each of which include aprojection optics projecting image light onto a screen.

2. Description of the Related Art

Conventionally, there has been known a projection-type image displaydevice having an optical modulator configured to modulate light emittedfrom a light source and a projection lens configured to project light,which is outputted from the optical modulator onto a screen.

To display a larger image on a screen, it is needed to take a longerdistance between the projection lens and the screen. Regarding thisbackground, there has been proposed a projection-type image displaysystem configured to shorten the distance between a projection-typeimage display device and a screen by utilizing a reflection mirrorreflecting light, which is outputted from the projection lens, towardthe screen (see, for example, Japanese Patent Publication No. 2004-45894(claim 1, FIG. 2, and the like)).

When the distance between the projection-type image display device andthe screen is shortened, the projection-type image display device comesclose to the screen and thus comes into sight of users. For this reason,an oblique projection is needed from an upper, lower, or lateral side ofthe screen. For example, in the above-mentioned projection-type imagedisplay system, positions of the optical modulator and the projectionoptics are shifted in vertical directions and a convex mirror is used asa reflection mirror, so that a projection distance is shortened and theoblique projection is performed with a shortened projection distance.

In addition, to shorten the distance between the projection-type imagedisplay device and the screen, the reflection mirror is disposed in sucha position at such an angle that light outputted from the projectionlens can obliquely enter the screen. For example, in the above-mentionedprojection-type image display system, a convex lens is used as thereflection mirror to shorten the distance between the projection-typeimage display device and the screen.

To properly display an image on a screen, the positioning of thereflection mirror is an element of substantial importance, Accordingly,when a user touches the reflection mirror, an angle or the like of thereflection mirror is changed, which obstructs proper display of an imageto be projected on the screen.

SUMMARY OF THE INVENTION

In an aspect of the present invention, a projection-type image displaydevice (a projection-type image display device 30) includes an imagelight generator (an image light generator 40), a projection optics (aprojection optics 300) having a reflection mirror (an aspherical mirror50), and a protective cover (a protective cover 60). The image lightgenerator generates image light, and the projection optics projects theimage light onto a screen (a screen 11). The reflection mirror in theprojection optics reflects the image light, which is outputted from theimage light generator, toward the screen. The protective cover isprovided on an optical path of the image light reflected by thereflection mirror, and has a transmissive region transmitting the imagelight reflected by the reflection mirror.

According to this aspect, since the protective cover is provided on theoptical path of the image light reflected by the reflection mirror, auser is less likely to touch the reflection mirror and change an angleand the like of the reflection mirror. Here, because the protectivecover has the transmissive region transmitting the image light reflectedby the reflection mirror, the image light to be irradiated on the screenwill not be interrupted by the protective cover.

Thus, even when the image light is being projected on the screen, thepositioning accuracy of the reflection mirror provided to shorten thedistance between the projection-type image display device and the screencan be preferably maintained.

In the above aspect of the present invention, the reflection mirrorcondenses the image light outputted from the image light generatorbetween the reflection mirror and the screen. The transmissive region ofthe protective cover is disposed in the vicinity of a position where theimage light is condensed by the reflection mirror (a light-condensingsurface a).

In the above aspect of the present invention, the protective cover hasan opening (an opening 161) communicating from the reflection mirrorside to the screen side. The transmissive region is the opening.

In the above aspect of the present invention, at least one portion ofthe protective cover is formed of a light transmitting member and thetransmissive region is formed of the light transmitting member.

In an aspect of the present invention, a projection-type image displaysystem (a projection-type image display system 100) includes a screen (ascreen 11), an image light generator (an image light generator 40), aprojection optics (a projection optics 300) having a reflection mirror(an aspherical mirror 50), and a protective cover (a protective cover60). The image light generator generates image light, and the projectionoptics projects the image light onto the screen. The reflection mirrorin the projection optics reflects the image light, which is outputtedfrom the image light generator, toward the screen. The protective coveris provided on an optical path of the image light reflected by thereflection mirror, and has a transmissive region transmitting the imagelight reflected by the reflection mirror.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view (seen from the front) showing a configuration of aprojection-type image display system 100 according to a firstembodiment;

FIG. 2 is a view (seen from a side) showing a configuration of theprojection-type image display system 100 according to the firstembodiment;

FIG. 3 is a view showing a configuration of a projection-type imagedisplay device 30 according to the first embodiment;

FIG. 4 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to a secondembodiment;

FIG. 5 is a view showing an aspherical mirror 50 according to the secondembodiment;

FIG. 6 is a view showing a light-condensing surface a according to thesecond embodiment;

FIG. 7 is a view showing a protective cover 160 according to the secondembodiment;

FIG. 8 is a view showing an aspherical mirror 50 according to a thirdembodiment;

FIG. 9 is a view showing a light-condensing surface a according to thethird embodiment;

FIG. 10 is a view showing a protective cover 160 according to the thirdembodiment;

FIG. 11 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to a fourthembodiment;

FIG. 12 is a view showing a configuration of an image light generator 40according to a fifth embodiment;

FIG. 13 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to a sixthembodiment;

FIG. 14 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to a seventhembodiment;

FIG. 15 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to an eighthembodiment; and

FIG. 16 is a view (seen from a side) showing a configuration of aprojection-type image display system 100 according to a ninthembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A projection-type image display device according to each embodiment ofthe present invention will be described below by referring to thedrawings. Note that same or similar reference numerals denote same orsimilar portions in the drawings.

Note that the drawings are merely schematic and proportions of sizes andthe like are different from actual ones. Thus, specific sizes and thelike should be determined by referring to the description below. Inaddition, needless to say, portions are included where relationships orproportions of sizes of the drawings differ among the drawings.

First Embodiment (Configuration of a Projection-Type Image DisplaySystem)

A configuration of a projection-type image display system according to afirst embodiment of the present invention will be described below byreferring to the drawings. FIG. 1 is a view (seen from the front)showing a configuration of a projection-type image display system 100according to the first embodiment. FIG. 2 is a view (seen from a side)showing a configuration of the projection-type image display system 100according to the first embodiment.

As shown in FIGS. 1 and 2, the projection-type image display system 100has a body 10, a base 20, and a projection-type image display device 30.

The body 10 has a shape extending in the vertical direction of theprojection-type image display system 100. The body 10 has a screen 11onto which an image is projected.

The base 20 is provided on a lower surface of the body 10 and supportsthe body 10. The base 20 has wheels 21 a and 21 b which make theprojection-type image display system 100 movable.

The projection-type image display device 30 has an image light generator40, a projection lens 41, an aspherical mirror 50, and a protectivecover 60, The projection-type image display device 80 is provided on anupper portion of the body 10. Here, the projection lens 41 and theaspherical mirror 50 configure a projection optics 300 as will bedescribed later (see, FIG. 3).

Note that in the first embodiment, the projection-type image displaydevice 30 is provided on an upper portion of the body 10 but theconfiguration is not limited to this.

Specifically, the projection-type image display device 30 may beprovided on a lower portion of the body 10. In this case, theprojection-type image display device 30 is disposed upside down.

In addition, the projection-type image display device 30 may be providedin the left or right portion of the body 10. In this case, theprojection-type image display device 30 is disposed in a state of beingrotated substantially 90°.

As shown in FIG. 3, the projection-type image display device 30 isconfigured of the image light generator 40 and the projection optics300. Note that the protective cover 60 is omitted in FIG. 3. The imagelight generator 40 has a power circuit (not shown) and an image signalprocessing circuit (not shown) in addition to an optical engine 200.

As shown in FIG. 3, the optical engine 200 has a light source 410, apair of fly-eye lenses 420, a PBS array 430, a plurality of opticalmodulators 440 (an optical modulator 440R, an optical modulator 440G,and an optical modulator 440B), and a cross dichroic prism 450.

The light source 410 is a UHP lamp configured of a burner and areflection mirror.

Each of the fly-eye lenses 420 is formed of a group of minimal lensesand uniform light beams outputted from the light source 410.

The PBS array 430 is an element for aligning the polarization directionsof the light beams outputted from the pair of fly-eye lenses 420.

Each of the optical modulators 440 is an element for modulating eachcolor component light based on an image signal. The optical modulator440 is, for example, a liquid crystal panel.

The cross dichroic prism 450 combines the light beams outputted fromeach of the optical modulators 440. Specifically, the cross dichroicprism 450 reflects a red component light outputted from the opticalmodulator 440R and a blue component light outputted from the opticalmodulator 440B. On the other hand, the cross dichroic prism 460 allowslight outputted from the optical modulator 440G to pass therethrough.Note that the light combined by the cross dichroic prism 450 enters theprojection lens 41.

The optical engine 200 has a plurality of lens groups (lenses 461 to466) and a plurality of mirror groups (mirrors 471, 472, and 481 to483).

The lens 461 is a condenser lens to cause the blue component light to besubstantially parallel beams so that the optical modulator 440B would beirradiated with the blue component light. The lens 462 is a condenserlens to cause the green component light to be substantially parallelbeams so that the optical modulator 440G would be irradiated with thegreen component light. The lens 466 is a condenser lens to cause the redcomponent light to be substantially parallel beams so that the opticalmodulator 440R would be irradiated with the red component light.

The lenses 463 to 465 are relay lenses to adjust a difference betweenthe optical path length of each of the blue component light and thegreen component light, and the optical path length of the red componentlight.

The mirror 471 is a dichroic mirror to reflect the blue component lightand to transmit the red component light and the green component light.The mirror 472 is a dichroic mirror to reflect the green component lightand to transmit the red component light.

The mirror 481 is a mirror to reflect the blue component light to leadthe blue component light to the optical modulator 440B. The mirrors 482and 483 are mirrors to reflect the red component light to lead the redcomponent light to the optical modulator 440R.

Note that in the first embodiment, the UHP lamp is used as the lightsource 410, but the configuration is not limited to this. Specifically,a solid light source such as an LED (a light emitting diode) or an LD (alaser diode) may be used as the light source 410. In this case, it isalso possible that a configuration of an optical system does not includefly-eye lenses 420, a PBS array 430, a plurality of lens groups, and aplurality of mirror groups.

As shown in FIG. 3, the projection optics 800 has the projection lens 41and the aspherical mirror 50. The projection lens 41 outputs the light(the image light) combined by the cross dichroic prism 450 provided inthe optical engine 200, to the aspherical mirror 50 side. The asphericalmirror 50 causes the image light outputted from the projection lens 41to have a wider angle and reflects the image light to the screen 11side.

The aspherical mirror 50 is attached to arm members 52 a and 52 b whichare fixed on a wall surface of the projection-type image display device30. The aspherical mirror 50 is an aspherical mirror to condense lightoutputted from the projection lens 41 and to reflect the light to thescreen 11 side.

Note that in the first embodiment, the mirror provided in a rear stageof the projection optics 300 is the aspherical mirror 50 but is notlimited to this. Specifically, the mirror provided in the rear stage ofthe projection optics 300 may be a free-form surface mirror.

Returning to FIG. 2, the protective cover 60 is provided on the opticalpath of the image light reflected by the aspherical mirror 50.Specifically, the protective cover 60 is provided beneath theprojection-type image display device 30 and covers a lower portion ofthe aspherical mirror 50 so as to prevent the aspherical mirror 50 frombeing touched by a user. The protective cover 60 is formed of a lighttransmitting member such as a transparent resin or a glass and transmitsthe image light reflected by the aspherical mirror 50.

Here, since optical characteristics (such as a refractive index) of theimage light irradiated onto the screen 11 vary depending on the kind ofthe light transmitting member forming the protective cover 60, it ispreferable that an optical design for the projection optics 300 be madein consideration of the kind of the light transmitting member formingthe protective cover 60.

(Advantageous Effects)

According to the projection-type image display device 30 of the firstembodiment, the protective cover 60 is provided on the optical path ofthe image light reflected by the aspherical mirror 50. Thus, the user isless likely to touch the aspherical mirror 50 to cause any change in anangle of the aspherical mirror 50 or the like. Since the protectivecover 60 is formed of the light transmitting member transmitting theimage light reflected by the aspherical mirror 50, the image lightirradiating onto the screen 11 is not interrupted by the protectivecover 60. Accordingly, positioning accuracy of the reflection mirrorprovided to shorten the distance between the projection-type imagedisplay device 30 and the screen 11 can be preferably maintained.

Second Embodiment

A second embodiment of the present invention will be described below byreferring to the drawings. In the following, differences between thefirst embodiment and the second embodiment will be described byreferring to the drawings.

Specifically, in the above-mentioned first embodiment, the protectivecover 60 protecting the aspherical mirror 50 is formed of the lighttransmitting member. In contrast, in the second embodiment, a protectivecover 160 has an opening through which image light condensed by anaspherical mirror 50 passes. Note that the protective cover 160 does notneed to be formed of a light transmitting member.

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe second embodiment of the present invention will be described belowby referring to the drawings. FIG. 4 is a view showing a configurationof a projection-type image display system 100 according to the secondembodiment. Note that in FIG. 4, similar reference numerals are given todenote components similar to those of FIG. 2. As shown in FIG. 4, theprojection-type image display system 100 has a protective cover 160 inplace of a protective cover 60.

(Configurations of an Aspherical Mirror and a Protective Cover)

Configurations of an aspherical mirror and a protective cover accordingto the second embodiment will be described below by referring to FIGS. 5to 7.

As shown in FIG. 5, an aspherical mirror 50 is a mirror having a curvedsurface 51 which is curved in horizontal directions and in verticaldirections of a projection-type image display system 100. Image lightreflected by the curved surface 51 of the aspherical mirror 50 isprojected onto a screen 11 after being condensed on a light-condensingsurface a. The light-condensing surface a is a surface where thebroadening of a light flux of the image light becomes the smallest.

Specifically, as shown in FIG. 6, on the light-condensing surface a, theimage light reflected by the curved surface 51 of the aspherical mirror50 is condensed in a region b having a particular shape depending on ashape of the curved surface 51 of the aspherical mirror 50. Note that inFIG. 6, the region b is shown as a region having an elliptic shape forsimplicity, but the actual shape of the region b becomes a morecomplicated shape.

The protective cover 160 has an opening 161 communicating from anaspherical mirror 50 side to a screen 11 side. The image light reflectedby the curved surface 51 of the aspherical mirror 50 is irradiated ontothe screen 11 through the opening 161 provided in the protective cover160.

Specifically, as shown in FIG. 7, the protective cover 160 is providedwith the opening 161 depending on a particular shape of the image lightcondensed in the region b. A size of the opening 161 is at least largerthan that of the region b in which the image light is condensed on thelight-condensing surface a. However, as long as the image lightreflected by the curved surface 51 of the aspherical mirror 50 istransmittable, a shape of the opening 161 can be any shape.

In addition, it is preferable that the opening 161 be provided in thevicinity of the light-condensing surface a to minimize the size of theopening 161. Here, the vicinity of the light-condensing surface a meansthat a distance from the light-condensing surface a is in a range of“d”. Here, “d” indicates a distance between the aspherical mirror 50 andthe light-condensing surface a on a main light beam of light beamspassing through the centers of optical modulators 440.

(Advantageous Effects)

According to the projection-type image display device 30 of the secondembodiment, the aspherical mirror 50 condenses the image light outputtedfrom the projection lens 41 in the region b on the light-condensingsurface a. Thus, the opening 161 provided in the protective cover 160can be minimized. Therefore, even when the opening 161 is provided inthe protective cover 160, a possibility of a user touching theaspherical mirror 50 can be reduced.

In addition, in a case where a transmissive region of the protectivecover 160 is formed of a light transmitting member, an optical designfor a projection optics 300 has to be made depending on the kind of thelight transmitting member. In contrast, according to the projection-typeimage display device 30 of the second embodiment, the transmissiveregion of the protective cover 160 is the opening 161, and there is noneed to consider the kind of the light transmitting member. Thus, theoptical design for the projection optics 300 is made easier.

Third Embodiment

A third embodiment of the present invention will be described below byreferring to the drawings. The description will be mainly given todifferences between the above-mentioned second embodiment and the thirdembodiment.

Specifically, in the above-mentioned second embodiment, the asphericalmirror 50 is a mirror having the curved surface 51 which is curved inthe vertical directions and in the horizontal directions of theprojection-type image display system 100. In contrast, in the thirdembodiment, an aspherical mirror 50 is a mirror having a curved surface51 which is only curved in vertical directions of a projection-typeimage display system 100.

In addition, in the above-mentioned second embodiment, the protectivecover 160 is provided with the opening 161 having a particular shapedepending on a shape of the curved surface 51 of the aspherical mirror50. In contrast, a protective cover 160 of the third embodiment isprovided with an opening 161 having a long rectangular shape inhorizontal directions of the projection-type image display system 100.

(Configurations of an Aspherical Mirror and a Protective Cover)

Configurations of an aspherical mirror and a protective cover accordingto the third embodiment will be described below by referring to FIGS. 8to 10.

As shown in FIG. 8, the aspherical mirror 50 is a mirror having a curvedsurface 51 which is only curved in vertical directions of theprojection-type image display system 100. Similar to the secondembodiment, image light reflected by the curved surface 51 of theaspherical mirror 50 is projected onto a screen 11 after being condensedon a light-condensing surface a.

Specifically, as shown in FIG. 9, on the light-condensing surface a, theimage light reflected by the curved surface 51 of the aspherical mirror50 is condensed in a region b having a particular shape depending on ashape of the curved surface 51 of the aspherical mirror 50. Note that inFIG. 9, the region b is shown as a region having a long rectangularshape in horizontal directions of the projection-type image displaysystem 100 for simplicity, but the actual shape of the region b becomesa more complicated shape.

Similar to the second embodiment, the protective cover 160 has anopening 161 communicating from an aspherical mirror 50 side to a screen11 side. The image light reflected by the curved surface 51 of theaspherical mirror 50 is irradiated onto the screen 11 through theopening 161 provided in the protective cover 160.

Specifically, as shown in FIG. 10, the protective cover 160 is providedwith an opening 161 having a long rectangular shape in horizontaldirections of the projection-type image display system 100. A size ofthe opening 161 is at least larger than that of the region b in whichthe image light is condensed on the light-condensing surface a. However,as long as the image light reflected by the curved surface 51 of theaspherical mirror 50 is transmittable, a shape of the opening 161 can beany shape.

Fourth Embodiment

A fourth embodiment of the present invention will be described below byreferring to the drawings. In the following, the description will bemainly given to differences between the above-mentioned secondembodiment and the fourth embodiment.

Specifically, in the above-mentioned second embodiment, the image lightoutputted from the projection lens 41 is reflected only once. Incontrast, the image light outputted from a projection lens 41 of thefourth embodiment is reflected for a plurality of times (three times).

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe fourth embodiment will be described below by referring to thedrawings. FIG. 11 is a view (seen from a side) showing a configurationof a projection-type image display system 100 according to the fourthembodiment. Note that in FIG. 11, similar reference numerals are givento denote components similar to those of FIG. 2.

As shown in FIG. 11, the projection-type image display system 100 hasreflection mirrors 70 and 80 in addition to the configuration of FIG. 2.

The reflection mirror 70 is a convex mirror reflecting image lightoutputted from a projection lens 41 to the reflection mirror 80 side. Inaddition, since the reflection mirror 70 is a convex mirror, the imagelight outputted from the projection lens 41 is enlarged. The reflectionmirror 80 is a concave mirror reflecting the image light reflected bythe reflection mirror 70 to an aspherical mirror 50 side. Note that theprojection lens 41, the reflection mirrors 70 and 80, and the asphericalmirror 50 configure a projection optics.

(Advantageous Effect)

According to a projection-type image display device 30 of the fourthembodiment, the image light outputted from the projection lens 41 isreflected not only by the aspherical mirror 60 but also by thereflection mirrors 70 and 80. Thus, even if a size in a depth directionof the projection-type image display device 30 is set to be small, theprojection-type image display device 30 can sufficiently enlarge andproject the image light outputted from the projection lens 41 on ascreen 11.

Fifth Embodiment

A fifth embodiment of the present invention will be described below byreferring to the drawings. In the following, the description will bemainly given to differences between the above-mentioned first embodimentand the fifth embodiment.

Specifically, in the fifth embodiment, an effective display region of amodulator 440 is provided in a portion lower than a projection lens 41,which is not particularly mentioned in the first embodiment.

(Configuration of an Image Light Outputting Device)

A configuration of an image light outputting device according to thefifth embodiment will be described below by referring to the drawings.FIG. 12 is a view showing a configuration of an image light generator 40according to the fifth embodiment. Here, the image light generator 40has a configuration similar to that of FIG. 3. Note that in FIG. 12,only components necessary for the description of the fifth embodimentare shown.

As shown in FIG. 12, in the image light generator 40, an effectivedisplay region of an optical modulator 440 is provided in a portionlower than a projection lens 41. Specifically, the effective displayregion of the optical modulator 440 is provided in a portion lower thanthe center L of an optical axis of the projection lens 41.

With this, the image light outputted from the projection lens 41 isoutputted obliquely upward from the projection lens 41. Thus, anaspherical mirror 50 reflecting the image light outputted from theprojection lens 41 to a screen 11 (not shown in FIG. 12) side isprovided in a position obliquely upward of the projection lens 41.

(Advantageous Effects)

According to the fifth embodiment, the effective display region of theoptical modulator 440 is provided in a portion lower than the projectionlens 41. Thus, the image light outputted from the projection lens 41 isoutputted obliquely upward from the projection lens 41. Accordingly,wider oblique projection can be achieved, so that the distance betweenthe projection-type image display device and the screen can be furthershortened.

Sixth Embodiment

A sixth embodiment of the present invention will be described below byreferring to the drawings. The sixth embodiment is a combination of thefirst and fifth embodiments.

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe sixth embodiment will be described below by referring to thedrawings. FIG. 13 is a view (seen from a side) showing a configurationof a projection-type image display system 100 according to the sixthembodiment. Note that in FIG. 13, similar reference numerals are givento denote components similar to those of FIG. 2.

As shown in FIG. 13, in the projection-type image display system 100,protective covers 261 and 262 are provided so as to cover a projectionlens 41 and an aspherical mirror 50. The protective cover 262 isprovided in the vicinity of a light-condensing surface a and is formedof a light transmitting member. The protective cover 262 has a shapecapable of transmitting a light flux having a particular shape, which iscondensed depending on the form of a curved surface 61 of the asphericalmirror 50. However, as long as image light reflected by the curvedsurface 51 of the aspherical mirror 50 is transmittable, the shape ofthe protective cover 262 can be any shape.

As a matter of course, the protective cover 261 does not need to beformed of a light-transmitting member. The aspherical mirror 50 is heldinside the protective cover 261 by a holding mechanism provided insidethe protective cover 261.

Seventh Embodiment

A seventh embodiment of the present invention will be described below byreferring to the drawings. The seventh embodiment is a combination ofthe second and fifth embodiments.

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe seventh embodiment will be described below by referring to thedrawings. FIG. 14 is a view (seen form a side) showing a configurationof a projection-type image display system 100 according to the seventhembodiment. Note that in FIG. 14, similar reference numerals are givento denote components similar to those of FIG. 4.

As shown in FIG. 14, in the projection-type image display system 100, aprotective cover 361 is provided so as to cover a projection lens 41 andan aspherical mirror 50. The protective cover 361 has an opening 862 inthe vicinity of a light-condensing surface a. The opening 362 has ashape capable of transmitting a light flux having a particular shape,which is condensed depending on the form of a curved surface 51 of theaspherical mirror 50. However, as long as image light reflected by thecurved surface 51 of the aspherical mirror 50 is transmittable, theshape of the opening 362 can be any shape.

The aspherical mirror 50 is held inside the protective cover 361 by aholding mechanism provided inside the protective cover 361.

Eighth Embodiment

An eighth embodiment of the present invention will be described below byreferring to the drawings. In the following, the description will bemainly given to differences between the above-mentioned sixth embodimentand the eighth embodiment.

Specifically, in the above-mentioned sixth embodiment, the protectivecover 262 formed of a light-transmitting member is provided in thevicinity of the light-condensing surface a. In contrast, in the eighthembodiment, a concave lens for projecting image light with a more widerangle is provided in the vicinity of the light-condensing surface a.Specifically, it is preferable that the concave lens be disposed on aside between the light condensing surface a and the screen 11, within arange “d” that extends on either side of the light-condensing surface a.

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe eighth embodiment will be described below by referring to thedrawings. FIG. 15 is a view (seen from a side) showing a configurationof a projection-type image display system 100 according to the eighthembodiment. Note that in FIG. 15, similar reference numerals are givento denote components similar to those of FIG. 13.

As shown in FIG. 15, in the projection-type image display system 100, aconcave lens 263 is provided in place of a protective cover 262 formedof a light-transmitting member.

The concave lens 263 is provided in the vicinity of the light-condensingsurface a. Specifically, the concave lens 263 is disposed on a sidebetween the light condensing surface a and the screen 11, within a range“d” that extends on either side of the light-condensing surface a. Theconcave lens 263 is configured so as to condense image light reflectedby an aspherical mirror 50. The concave lens 268 preferably has aconcave surface on the aspherical mirror 50 side, and plane surface onthe screen 11 side. The projection optics is preferably surrounded withthe protective cover 261 of flat shape. That is, the projection opticsis surrounded with the plane surface provided on the concave lens 263and the protective cover 261 of flat shape. Therefore, accumulation ofdusts on the exterior surface of the protective cover 261 and theconcave lens 263 may be suppressed.

In the eighth embodiment, a projection lens 41, the aspherical mirror 50and the concave lens 263 configure a projection optics 300 projectingthe image light onto the screen 11.

In addition, in the eighth embodiment, the concave lens 263 is used inplace of the protective cover 262, but the configuration is not limitedto this. Specifically, an aspherical lens or a free-form surface lensmay be used in place of the protective cover 262.

In this manner, since the concave lens 263 is provided in the vicinityof the light-condensing surface a, the distance between aprojection-type image display device and the screen can be furthershortened when compared with the distance in the sixth embodiment.

the concave lens 263 is disposed on a side between the light condensingsurface a and the screen 11, within a range “d” that extends on eitherside of the light-condensing surface a. That is, the concave lens 263condenses re-scattered image light after the image light is condensed onthe light-condensing surface a. Thus, an effect of a wider angle by useof the concave lens 263 can be further achieved.

Ninth Embodiment

A ninth embodiment of the present invention will be described below byreferring to the drawings. In the following, the description will bemainly given to differences between the above-mentioned seventhembodiment and the ninth embodiment.

Specifically, in the above-mentioned seventh embodiment, the projectionoptics 300 is configured of the projection lens 41 and the asphericalmirror 50. In contrast, in the ninth embodiment, a projection optics 300does not include a projection lens 41 and is configured of a pluralityof mirror groups.

(Configuration of a Projection-Type Image Display System)

A configuration of a projection-type image display system according tothe ninth embodiment will be described below by referring to thedrawings. FIG. 16 is a view (seen from a side) showing a configurationof a projection-type image display system 100 according to the ninthembodiment. Note that in FIG. 16, similar reference numerals are givento denote components similar to those of FIG. 14.

As shown in FIG. 16, in the projection-type image display system 100, aplurality of mirror groups (mirrors 151 to 155) is provided in place ofa projection lens 41 and an aspherical mirror 50. Note that the mirrors151 to 155 configure a projection optics 300.

In the ninth embodiment, the mirrors 151, 152, 154, and 155 are concavelenses and the mirror 153 is a convex lens, but of course, thecombination of the mirrors is not limited to this.

In the ninth embodiment, an opening 362 is provided in the vicinity ofthe light-condensing surface a, but the configuration is not limited tothis. Specifically, like the sixth embodiment, a protective cover 262formed of a light-transmitting member may be provided in the vicinity ofthe light-condensing surface a. Or, like the eighth embodiment, aconcave lens 263 condensing image light reflected by the mirror 155provided in the last stage of the projection optics 300 may be providedin the vicinity of the light-condensing surface a.

Other Embodiments

The present invention has been described by the above-mentionedembodiments, but the description and drawings which constitute a part ofthis disclosure should not be understood as to limit the scope of thepresent invention. For those who are skilled in the art, variousalternative embodiments, examples, and operating techniques will beapparent from this disclosure.

For example, in the above-mentioned first embodiment, the entireprotective cover is formed of a light-transmitting member, but theconfiguration is not limited to this. Specifically, it is only neededthat a protective cover has a transmissive region transmitting imagelight condensed by an aspherical mirror 50 and only the transmissiveregion is formed of a light-transmitting member. Since the asphericalmirror 50 condenses the image light, the size of the transmissive regioncan be minimized, so that the light-transmitting member forming thetransmissive region can be easily maintained.

In the second and third embodiments, shapes of the openings 161 providedin the protective covers 160 are an elliptical shape and a rectangularshape which is long in horizontal directions of the projection-typeimage display system 100, but are not limited to those. Specifically,the shape of the opening 161 provided in the protective cover 160 isdetermined depending on the shape of condensed image light (a region b)condensed by the aspherical mirror 50 on the light-condensing surface a.

In the second to eighth embodiments, an aspherical mirror is used as amirror reflecting image light outputted from a projection lens 41 to thescreen 11 side, but the mirror is not limited to this. Specifically, afree-form surface mirror may be used as a mirror reflecting the imagelight outputted from the projection lens 41 to the screen 11 side. If anaberration and a resolution can be adjusted, a spherical mirror may beused as a mirror reflecting the image light outputted from theprojection lens 41 to the screen 11 side.

According to each of the above mentioned embodiments, a reflectionmirror is provided so that a distance between a projection-type imagedisplay device and a screen can be shortened. Thus, it is less likelythat image light is interrupted by a person or the like coming inbetween the projection-type image display device and the screen. Inaddition, in a case where an LD is used as a light source 410, thepossibility that a person is accidentally irradiated with the laser beam(image light) can be reduced.

In the above-described embodiments, the display system provided with thescreen of reflective type is explained. However, a screen oftransmitting type may be applicable.

1. A projection-type image display device comprising: an image lightgenerator configured to generate image light; a projection opticsconfigured to project the image light onto a screen, the projectionoptics including a reflection mirror configured to reflect the imagelight toward the screen, the image light outputted from the image lightgenerator; and a protective cover provided on an optical path of theimage light reflected by the reflection mirror, wherein the protectivecover has a transmissive region transmitting the image light reflectedby the reflection mirror.
 2. The projection-type image display deviceaccording to claim 1, wherein the reflection mirror condenses the imagelight between the reflection mirror and the screen, the image lightoutputted from the image light generator and the transmissive region ofthe protective cover is disposed in a vicinity of a position where theimage light is condensed by the reflection mirror.
 3. Theprojection-type image display device according to claim 1, wherein theprotective cover has an opening communicating from the reflection mirrorside to the screen side and the transmissive region is the opening. 4.The projection-type image display device according to claim 1, whereinat least one portion of the protective cover is formed of alight-transmitting member and the transmissive region is formed of thelight-transmitting member.
 5. A projection-type image display systemcomprising: a screen; an image light generator configured to generateimage light; a projection optics configured to project the image lightonto the screen, the projection optics including a reflection mirrorconfigured to reflect the image light toward the screen, the image lightoutputted from the image light generator; and a protective coverprovided on an optical path of the image light reflected by thereflection mirror, wherein the protective cover has a transmissiveregion transmitting the image light reflected by the reflection mirror.